Scientists estimate that we reached Peak Superhero in the summer of 2008, when “The Dark Knight” sucked the attention of every critic, pundit and sentient moviegoer into its inky nexus. It is not as if the number of movies featuring troubled guys wearing costumes and fighting evil has diminished since then. Quite the contrary. But the genre, though it is still in a period of commercial ascendancy, has also entered a phase of imaginative decadence. (Do you really want to have an argument about this? If so, put on your best oversize metal suit and wait for me at the top of the New York Times building. I’ll be there as soon as I finish beta-testing my death ray. Apologies in advance to any commuters crushed by flying debris.) The latest evidence — though it is unlikely to be the last, with a new “Spider-Man” and another “Dark Knight” looming on the horizon — is “Marvel’s The Avengers.”

You may occasionally encounter (as I have, a few times in the past months) a walking relic of an earlier era of pop-cultural fandom who wonders if they have, at last, made another movie out of that fondly recalled British spy series from the 1960s. “They” have not, and those poor souls who cherish old daydreams of Diana Rigg in leather will have to console themselves with images of Scarlett Johansson in a black bodysuit.

So “The Avengers,” which has been foreshadowed by post-credits teasers in (deep breath), “Captain America,”“Thor,”“The Incredible Hulk” (the one with Edward Norton) and both “Iron Man” pictures, is not without its pleasures. Written and directed by Joss Whedon, this movie revels in the individuality of its mighty, mythical characters, pinpointing insecurities that are amplified by superhuman power and catching sparks that fly when big, rough-edged egos (and alter egos) collide. The best scenes are not the overblown, skull-assaulting action sequences — which add remarkably little that will be fresh or surprising to devotees of the “Transformers” franchise — but the moments in between, when the assembled heroes have the opportunity to brag, banter, flirt and bicker.

The secret of “The Avengers” is that it is a snappy little dialogue comedy dressed up as something else, that something else being a giant A.T.M. for Marvel and its new studio overlords, the Walt Disney Company. At times — when various members of a game and nimble cast amble in and out of the glassy, metallic chambers of a massive flying aircraft carrier, cracking wise, rolling eyes and occasionally throwing a punch — the movie has some of the easygoing charm of “Rio Bravo,” Howard Hawks’s great, late western in which John Wayne, Angie Dickinson, Dean Martin and Ricky Nelson did a lot of talking on their way to a big and not-all-that-interesting shootout.

The difference is that, in keeping with the imperatives of global franchise entertainment, the big shootout in “The Avengers” must be enormous, of a scale and duration that obliterates everything else. A hole opens in the sky, disgorging metallic warriors on Jet Skis and big snakey things that inflict serious digital damage on the Manhattan skyline. Before that there are similarly overdone combat sequences. None of them matches, in cinematic wit or visceral surprise, a sucker punch landed by the Hulk on Thor’s lantern jaw or a cartoonish smackdown delivered by that same angry green fellow on Loki, Thor’s adoptive brother and this episode’s main villain.

Loki (Tom Hiddleston), a disgraced Asgardian princeling with a spear and magic helmet, is after the tesseract, a glowing blue cube of pure energy. With the help of a couple of brainwashed turncoats, Loki has pried it away from Nick Fury (Samuel L. Jackson), a world-government spymaster with a lot of semi-secret projects up his sleeve. He assembles a team to get it back, consisting of the guys we’ve seen in the other movies (including Clark Gregg as Agent Coulson, the series’s hardest-working nonsuperhero and its most reliable comic asset), as well as Ms. Johansson’s Black Widow. Eventually Jeremy Renner’s Hawkeye joins up too, mostly to glower and shoot a lot of arrows.

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Robert Downey Jr. in "The Avengers."Credit
Walt Disney Pictures

Mr. Jackson, with an eye patch and his well-practiced bellow, is more master of ceremonies than mission commander, and under his watch the Avengers indulge in some Rat Pack-y horsing around. Captain America (Chris Evans) is teased for being an out-of-touch old-timer, Thor for being a longhaired deity from another planet. Tony Stark (Robert Downey Jr.) is his usual mischievous playboy self, distinguishable from Sherlock Holmes at this point thanks only to his accent and the brief presence of Gwyneth Paltrow in his penthouse. The newcomer — and every intellectual’s favorite comic-book-based movie character from now on — is Mark Ruffalo as Bruce Banner, a mopey, hesitant genius who turns large and green when angry.

“I’m always angry,” he says at one point, and while “The Avengers” is hardly worth raging about, its failures are significant and dispiriting. The light, amusing bits cannot overcome the grinding, hectic emptiness, the bloated cynicism that is less a shortcoming of this particular film than a feature of the genre. Mr. Whedon’s playful, democratic pop sensibility is no match for the glowering authoritarianism that now defines Hollywood’s comic-book universe. Some of the rebel spirit of Mr. Whedon’s early projects “Buffy the Vampire Slayer,”“Firefly” and “Serenity” creeps in around the edges but as detail and decoration rather than as the animating ethos.

“I aim to misbehave,” Malcolm Reynolds famously said in “Serenity.” But for all their maverick swagger, the Avengers are dutiful corporate citizens, serving a conveniently vague set of principles. Are they serving private interests, big government, their own vanity, or what? It hardly matters, because the true guiding spirit of their movie is Loki, who promises to set the human race free from freedom and who can be counted on for a big show wherever he goes. In Germany he compels a crowd to kneel before him in mute, terrified awe, and “The Avengers,” which recently opened there to huge box office returns, expects a similarly submissive audience here at home. The price of entertainment is obedience.